The present invention generally relates to an optic fiber coupler and more particularly relates to robust, removable, optic fiber coupler which allows for a simple, passive optic fiber alignment without concern for large mechanical discrepancies of slight contamination between the couplers as found in severe environments within the manufacturing industries.
Coupling or connecting optic fibers is well known in prior art. However, the prior art, as discussed below, consists of permanent of semi-permanent couplers or connector which use various precise means to connect fiber optic cables, thereby precisely aligning the cables.
U.S. Pat. No. 3,829,195 (Rawson) utilizes two permanently attached, movable, graded index-of-refraction cylindrical segments of unequal length precisely adjusted by a micromanipulator to splice together optic fibers to achieve precise highly efficient coupling of two optic fibers.
U.S. Pat. No. 4,268,112 (Peterson) teaches permanently connecting optic fibers by precisely placing the two fiber ends into the same connector. In addition, the connector utilizes two solid hemispherical lenses to expand the light and an optically transmissive material to assist in transmitting the optic signals between fibers.
U.S. Pat. No. 4,718,746 (Chrepta) utilizes a single, bored, graded index rod to connect to two precisely placed optic fibers. In addition, the bore is filled with a gel to protect against contamination.
U.S. Pat. No. 4,889,406 (Sezerman) teaches the use of spherical lenses at the end of two optic fibers, and the optic fibers are inserted into each end of a precisely machined mechanical fitting which is angularly adjusted by manipulating fine adjustment screws on the mechanical fitting.
The use of optic fibers for transmission of data or optical information is becoming more and more prevalent throughout industries. An optic fiber, made of silica glass or other appropriate material surrounded by a suitable material, is essentially a "light tube" or waveguide in which light energy travels in a controlled manner. To make the optic fiber durable and somewhat manageable, the fiber is shielded in a protective and insulating material, thus creating an optic fiber cable. The goal in end-to-end coupling of two optic fiber cables is to maximize the transfer of light energy from a transmitting cable to a receiving cable, thereby allowing for accurate transmission of data.
Optic fiber coupling technology is desired in many situations in which precision placement or close tolerance alignment of these extremely fine fibers is not mechanically or economically feasible. For example, optic fiber data transmission in the area of robotics is desired by manufacturers, but the tolerance in the fit between a robotic arm and a "quick-change" and effector is insufficient to allow optic fiber coupling via techniques described in the above prior art.
To allow for large mechanical displacements between optic fiber ends as would occur in robotic applications, the invention described herein utilizes a removable coupler device containing a gradient refractive index (GRIN) lens, and the device attaches to the end of an optic fiber. Two optic fibers are coupled simply by placing, holding, or positioning the end faces of the couplers parallel to each other such that the GRIN lenses are coaxially aligned. The invention does not require both couplers to be positioned within a precision mechanical sleeve to obtain proper alignment. The invention does allow for larger mechanical displacements, well within the tolerances of the interface between a robotic arm and a quick change end effector.